@AfricaOffroad I have 2 units. They run on Reefcrest Random mode on anti-sync. The slave unit has been working but it does not run smoothly. What it does is it 'gallops'. It seems the power supply from the controller is not constant. As I explained in anther thread some time back, it runs like a car enjine which has a racing cam. It cannot idle smoothly / constantly. So it is in constant state of either acceleration or deceleration if you can understand what mean. The faster the speed setting the worse the jurking action is. I could live with this as I have them running on Reefcrest Random which does not get to full speed. The master unit stopped working last week with the light displaying red. The motor does not spin at all. I stripped this one out and wanted the slave to work independantly meaning to be able to change the setting on it as it was the only unit still running. I wanted to change the speed up on the blue mode as flow has been lost due the the other pump being down, and it would not change to any other settings. It currently is running but it's running very slowly.

Do the controllers have close line of sight. Mine gave me crap a few years back because they werent close enough despite having line of sight. Otherwise try and reprogram them by clearing the memory and creating the master and slave again.

If they are broken, you will have to return them to where you bought them or a pet shop that keeps Aquarium Depot stuff, who will in turn send them to Aquarium depot in Joburg for repairs. Unfortunately AD wont allow you to go directly to them and only via a pet shop so you may have to buy a few cheap sun suns to keep you going while they are repaired as it could be a while

Add 1 tablespoon of 30% hydrogen peroxide per 100 litres every 4 hours to your tank in a power failure to oxygenate your water